Brake rotor assembly and method for making same

ABSTRACT

A method for forming a brake assembly for a motor vehicle includes a wheel hub, a knuckle, and a brake rotor. The wheel hub includes a neck portion and a flange portion having a flange face. The flange face has a plurality of bolt receiving holes formed therein. The wheel hub is placed in rotational communication with the knuckle. The flange face of the wheel hub has a brake rotor secured thereto. The brake rotor has an inner surface, which is subjected to final finishing in order to reduce lateral run-out of the brake rotor.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 09/803,785, now U.S. Pat. No. 6,708,589 filed on Mar. 12, 2001,which is a continuation-in part of U.S. patent application Ser. No.09/414,113, now U.S. Pat. No. 6,485,109, filed on Oct. 8, 1999 andentitled “Knuckle Hub Assembly and Method of Making Same” which claimspriority from provisional application, Ser. No. 60/136,535, filed on May28, 1999.

TECHNICAL FIELD

The present invention relates generally to motor vehicle wheel endcomponents. More particularly, the present invention relates to a brakeassembly having a unique configuration and manufacturing process forreducing lateral run-out and a unique apparatus for machining the outerbraking surfaces of a brake rotor.

BACKGROUND ART

Most motor vehicles today include disc brake systems for the front axlewheel assemblies and many further include disc brakes at the rear axleposition. The disc brake rotor is a circular metal disc having opposedbraking surfaces that are clamped by brake pads carried by a brakecaliper to exert a braking effect. The wheel hub typically incorporatesan anti-friction wheel bearing assembly in which one race of the bearingis coupled to the vehicle suspension and the other rotationally mountsthe wheel hub, the brake rotor and wheel. Ordinarily, the rotatingcomponents of the rotor and hub assembly are manufactured separately andassembled together. This enables the brake rotor to be serviced andreplaced if necessary during use. Moreover, the desired materialcharacteristics for a brake rotor and the hub components are different.Although efforts to integrate these components have been proposed, suchan approach has not found widespread acceptance.

In order to enhance performance of the braking system, it is desired tocarefully and accurately control the dimensional characteristics of therotor braking surfaces as the rotor rotates. The thickness variation ofthe disc and the lateral run-out or lateral deflection of the surfacesas they rotate need to be held to minimum tolerances. However,manufacturers have faced difficulties in achieving enhanced control overthese tolerances due to the influence of several factors.

Most efforts to date have focused on decreasing run-out by controllingthe dimensional characteristics of the rotor and therefore therelationship of the rotor surface to the wheel hub flange or surface.However, despite the fact that the tolerances and dimensionalcharacteristics of the rotors have improved, performance and run-outproblems still exist. These run-out problems are due in large part toother components of the wheel end assembly, including the bearing/hubassembly, which is comprised of a wheel hub and a bearing or theknuckle/hub assembly, which is comprised of a knuckle, a wheel hub, anda bearing.

One factor that contributes to this run-out is the stack-up of theindividual components in a rotor/knuckle/hub assembly, i.e., theircombined tolerances. While the tolerances of each part can be reducedwhen they are separately machined, when the parts are assembled, thecombined tolerances stack up, causing run-out that is still relativelysignificant. Another factor that contributes to stack-up is anyvariation in the turning processes that are used to machine the wheelhub flange surface or the rotor surface, when the wheel hub and therotor are individually machined, in an effort to make them flat.Further, the installation and press condition of the wheel bolts, theassembly process of the rotor/knuckle/hub assembly, and improperlypre-loaded bearings, can all cause misalignment of the rotor surfacewith respect to the brake pads and thus cause unacceptable run-out. Thisrun-out can cause premature failure of the brake lining due to unevenwear which requires premature replacement of the brake lining at anincreased expense. Further, problems due to run-out include, brakejudder, steering wheel “nibble” and pedal pulses felt by the user, andwarped rotors which result in brake noise and uneven stopping.

Presently available manufacturing methods and designs of rotors andknuckle hub assemblies to which the rotors are attached limit theaccuracy to which lateral run-out of braking surfaces can be controlled.These methods and designs are also insufficient to solve the problemsassociated with run-out, as discussed above. Current methods typicallyinvolve finishing the rotor and the hub individually and then assemblingthe machined parts to form a completed brake rotor assembly. Thesemethods, however, do not solve the run-out problems due to the factorsdiscussed above, including stack-up tolerances, turning processvariations, and wheel bolt and bearing installations.

Other options have been considered in an effort to solve the run-outproblem, but they also all suffer from a variety of disadvantages. Onecontemplated option for reducing run-out is to separately decrease therun-out of each individual component, by decreasing their respectivetolerances during manufacture and then assembling the components. The“stack up” of tolerance variations related to such an approach is stillsignificant and provides only limited system improvement at an increasedmanufacturing cost. Another contemplated option includes tightening thepress-fit tolerance variation between the knuckle, the wheel hub, andthe bearing. This, however, significantly increases the difficulty inthe assembly process as well as increases the manufacturing cost.Further, this option does not provide the desired reduction in systemrun-out.

It would therefore be advantageous to design a brake assembly for amotor vehicle that decreases system run-out without significantlyincreasing the manufacturing cost of the assembly or increasing themanufacturing difficulty.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a brakeassembly and a method for manufacturing same that provides reduced brakerotor lateral run-out.

It is a further object of the present invention to provide a brakecorner assembly and a method for manufacturing same that results in abrake configuration which minimizes brake noise and uneven stopping.

It is still a further object of the present invention to provide a brakeassembly and method for manufacturing same that results in a brakeconfiguration which minimizes uneven brake lining wear and thus the needfor frequent lining replacements.

It is a related object of the present invention to provide a brakeassembly and a method for manufacturing same that results in a brakeconfiguration which increases the life of vehicle brake linings.

It is yet another object of the present invention to provide a brakeassembly and a method for manufacturing same that results in a brakeconfiguration which provides improved performance at relatively lowercost.

It is yet a further object of the present invention to provide a tool toallow for the machining of a brake assembly to provide decreased lateralrun-out on the outboard and inboard brake rotor faces.

In accordance with the objects of the present invention a brake assemblyfor a motor vehicle is provided. The brake assembly includes a knucklehaving a plurality of apertures formed therein for attachment of theknuckle to a vehicle. The knuckle also includes a bearing retentionportion. The knuckle bearing retention portion is in communication witha bearing through press-fitting. The bearing in turn is in rotationalcommunication with a wheel hub. The wheel hub includes a neck portionthat is pressed into the bearing, and a flange, having a flange face.The flange face has a plurality of bolt holes formed therein with eachof the plurality of bolt holes receiving a wheel bolt passedtherethrough. The flange face has a brake rotor secured thereto, whichis finished such that it is parallel to the caliper mounting features,and wherein the brake rotor has minimal run out with respect to thebearing axis of rotation.

In accordance with another object of the present invention, a method forforming a knuckle/hub assembly having reduced run-out is provided. Themethod includes providing a knuckle having a generally circular boreformed therein. The generally circular knuckle bore has a bearingpress-fit therein. A wheel hub having a neck portion and a flangeportion with a flange face is provided. The flange face has a pluralityof wheel bolts press-fit into bolt holes formed therein. The neckportion of the wheel hub is then journaled into the bearing such thatthe wheel hub can rotate with respect to the knuckle. A brake rotor isthen secured to the wheel hub by locating it over the wheel bolts. Oncethe brake rotor is assembled to the wheel hub, the brake rotor surfacesare then final finished such that they are co-planar and parallel withrespect to the caliper ears or pads.

In accordance with another object of the present invention, an assemblyfor holding a brake assembly while it is final finished is provided. Theassembly includes a standard lathe machine with a fixture for clampingand locating the knuckle/hub assembly. The fixture applies a clampingforce to the wheel hub and the inner race of the bearing to generate apre-load on the bearing. The fixture also holds the knuckle in place sothat the wheel hub may be rotated. Thereafter, the inner surface of therotor is final finished so that it is flat and planar so as to provideminimal run-out when measured back to the brake assembly's axis ofrotation.

These and other features and advantages of the present invention willbecome apparent from the following description of the invention whenviewed in accordance with the accompanying drawings and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a knuckle/hub assembly in accordancewith a preferred embodiment of the present invention;

FIG. 2 is an exploded cross-sectional view illustrating the componentsof a knuckle/hub assembly and a brake rotor in accordance with apreferred embodiment of the present invention;

FIG. 3 is a cross-sectional view of the brake assembly in accordancewith a preferred embodiment of the present invention;

FIG. 4 is a rear view of a knuckle/hub assembly in accordance with apreferred embodiment of the present invention;

FIG. 5 is an end view of a wheel hub flange face in accordance with apreferred embodiment of the present invention;

FIG. 6 is a cross-sectional view of the wheel hub of FIG. 5 along theline 6-6;

FIG. 7 is a top view of a manufacturing fixture assembly for use in thegeneration of a knuckle/hub assembly in accordance with a preferredembodiment of the present invention;

FIG. 8 is a bottom view of a manufacturing fixture assembly with aknuckle/hub assembly clamped therein in the direction of the arrow 8 inFIG. 9 in accordance with a preferred embodiment of the presentinvention;

FIG. 9 is a cross-sectional view of the manufacturing fixture assemblyand brake assembly clamped therein of FIG. 7 in the direction of thearrows 9-9;

FIG. 10 is a cross-sectional view of a puller member of themanufacturing fixture assembly of FIG. 7 in the direction of the arrows10-10;

FIG. 11 is a cross-sectional view of the manufacturing fixture assembly,with a knuckle/hub assembly positioned therein, of FIG. 9 in thedirection of the arrows 11-11;

FIG. 12 is a cross-sectional view of the manufacturing fixture assembly,with a knuckle/hub assembly positioned therein, of FIG. 9 in thedirection of the arrows 12-12;

FIG. 13 is a rear view of a brake assembly in accordance with apreferred embodiment of the present invention; and

FIG. 14 is a cross-sectional side view of a brake assembly in accordancewith a preferred embodiment of the present invention.

BEST MODE(S) OF THE INVENTION

FIGS. 1 through 4 illustrate a preferred knuckle/hub assembly, asgenerally indicated by reference number 10, in accordance with thepresent invention. The assembly 10 is comprised of a variety ofcomponents, including a knuckle 12 and a wheel hub 14. The knuckle 12 ispreferably constructed of metal and is generally formed by casting whilethe wheel hub 14 is preferably constructed of metal. The knuckle and hubcan obviously be formed of other materials. The knuckle 12 preferablyhas a generally circular bore 16 formed therein and a plurality ofoutwardly extending appendages 18 that attach to the vehicle through aplurality of apertures 20 formed in the plurality of legs 18, as is wellknown in the art.

The bore 16 has a recess 22 formed therein bounded by an upper snap ringgroove 24 and a lower snap ring 26 or shoulder for receiving a bearing28 press fit therein. A snap ring 29 is preferably press fit orotherwise secured into the upper snap ring groove 24 prior to engagementof the bearing 28 with the knuckle 12. It should be understood thatwhile the illustrated assembly has a bore 16 formed in the knuckle 12,the bearing 28 can be attached or secured to the knuckle 12 in a varietyof configurations. For example, the bearing 28 can be mounted to anupper surface or other portion of the knuckle 12. Alternatively, thebearing 28 can be only partially disposed in the bore 16. Additionally,the bore 18 can be eliminated altogether.

The bearing 28 preferably has an outer race 31 and an inner race 33.However, it should be understood that a variety of different bearingsmay be utilized as well as a variety of different knuckle/bearingattachment configurations. For example, instead of being press-fit witha snap ring, i.e., between the upper retention ring 24 and the lowerretention ring 26, the bearing 28 may be press-fit without a snap ringand held in place with a nut or other known securing methods.Alternatively, the outer race 31 may be integrally formed with theknuckle 12 or may be configured as an orbital formed outer race rotationbearing/knuckle assembly. Further, the bearing outer race 31 couldalternatively be bolted to the knuckle 12 such that the inner race 33rotates with the wheel hub 14. Moreover, the inner race 33 may beintegrally formed with the wheel hub 14. Further, a spindleconfiguration having a non-driven outer race rotation may also beutilized.

In the preferred embodiment, the wheel hub 14 has a neck portion 30 anda flange portion 32. The neck portion 30 is preferably pressed intocontact with the inner race 33 of the bearing 28 so that the wheel hub14 can rotate with respect to the knuckle 12, as shown in FIG. 3.Alternatively, the neck portion 30 may be integrally formed with theinner race 33 or the outer race 31. It should be understood that otherwheel hub/bearing configurations may also be utilized.

The flange portion 32 has a flange face 34 and a wheel and rotor pilotportion 36. The wheel and rotor pilot portions 36 extend generallyupwardly from the flange face 34 and has an inner surface 38, whichdefines a spline 40. The wheel hub 14 also has a plurality of bolt holes42 formed in the flange face 34 through which a plurality of respectivewheel bolts 44 are passed. The plurality of wheel bolts 44 are attachedto the flange face 34 in a predetermined pattern and on the same pitchcircle diameter. The wheel bolts 44 are oriented with the threaded endsextending outwardly so as to connect a rotor 46 (FIGS. 2 and 3) andassociated wheel onto the hub 14 in a fashion, which is more clearlydescribed below. Alternatively, the wheel hub 14 may have bolt holes 42that receive lug nuts that are attached to a vehicle wheel and arepassed through the bole holes 42 when the wheel is attached to the wheelhub 14.

As best shown in FIGS. 2 and 3, the rotor 46 comprises a cup 48 with acentral aperture 50 adapted to receive therethrough a wheel shaft (notshown) affixed to the wheel and rotor pilot portions 36 and extendingoutwardly from the flange face 34. The cup 48 is dimensioned to receivethe hub flange portion 32 and includes at its outer end an annularflange 52 having a plurality of apertures 54 lying in the same pitchcircle diameter relative to the wheel shaft as the wheel bolts 44 andhaving a similar pattern so as to accommodate the wheel bolts 44therethrough.

A pair of parallel, annular discs 56 spaced from each other by aplurality of rectangular fillets 58 extend outwardly from the cup 48 anddefine braking surfaces for a plurality of brake calipers (not shown)The completion of the assembly to the wheel is done by positioning thewheel over the bolts 44 and the threading nuts (not shown) over thebolts 44 so as to secure the wheel between the nuts and the rotor 46.This invention addresses, among other things, the problems, which occurbetween the mating surfaces of the hub flange portion 32 and the rotor46.

Turning now to FIGS. 5 and 6, which illustrate the preferred wheel hub14 and flange portion 32 of the present invention. The flange face 34has a relief channel 60 machined therein. It should be understood thatthe relief channel 60 may also be forged into the flange face 34 or maybe formed by other known methods. The relief channel 60 divides theflange face 34 into an outer flange surface 62 and an inner flangesurface 64. The relief channel 60 is turned into the flange face 34 sothat the plurality of bolt holes 42 lie in the relief channel 60. Theplurality of bolt holes 42 may be formed either before or after therelief channel 60 has been formed. The relief channel is preferably setbelow the level of the flange face 34, this is to eliminate any surfaceunevenness caused by press-fitting the wheel bolts 44 into the boltholes 42. Any unevenness due to press-fitting of the wheel bolts 44 iscompensated for by the relief channel 60 as any unevenness will not beraised with respect to the flange 62, 64, and therefore does notcontribute to any run-out. The relief channel 60 also allows for finalfinishing or finish turning to be performed on the assembly 10 after thebolts 44 have been seemed to the wheel hub 14.

The relief channel 60 is preferably formed in the flange surface 34prior to the knuckle 12, the bearing 28, and the wheel hub 14 beingassembled. However, it should be understood that the relief channel 60can be formed in the flange surface 34 after the wheel hub 14 isassembled to the bearing 28 and the knuckle 12 and before the wheelstuds 44 are press-fit therein. In accordance with the preferred methodof forming, the wheel hub 14 has the relief channel 60 formed therein.Thereafter, the outer flange surface 62 and the inner flange surface 64are finished. After the finishing process has been completed, the wheelbolts 44 are press fit into the bolt holes 42. Thereafter, the hub 14 ismounted to the bearing 28 and the knuckle 12 to form the completedknuckle/hub assembly 10.

The assembly 10 is then placed into a clamping apparatus, as isdiscussed in more detail below, where it is finish turned or finalfinished to provide a flat outer flange surface 62 and a flat innerflange surface 64 that will contact the rotor 46 and thus, minimize anyrun out. The refinishing will provide an inner flange surface 64 and anouter flange surface 62 that are co-planar with respect to each other soas to provide a flat flange surface 34. The re-finishing processminimizes run-out with respect to not only the rotor, but also to thecenter of rotation of the assembly 68, as established by the bearing 28.Further, the method and configuration of the present invention allowsthe distance between the caliper ears and the flange surfaces 62, 64 tobe accurately controlled. Additionally, the parallelism between thecaliper ears and the flange surfaces 62, 64 can also be accuratelycontrolled. In the preferred embodiment, each flange surface has aflatness of 20 μm or better. Additionally, the run-out is minimized to14 μm or better and the co-planarness of the inner and outer surfaces62, 64 is 20 μm or better. However, the flatness requirements may bevaried.

FIGS. 7 through 12 illustrate a preferred part clamping fixture 70 inaccordance with the present invention. The part clamping fixture 70 ispreferably incorporated into a lathe machine (not shown) and is used tolocate and hold the brake assembly 300 in which is comprised of therotor 46 attached to the knuckle/hub assembly 10 for refinishing, inaccordance with the process described above.

As shown in FIG. 7, the part clamping fixture 70 includes a generallyflat top surface 72 for abutting a portion or surface of the lathemachine. The generally flat top surface 72 includes an opening 74 formedtherein in which a split collar 76 is generally positioned forengagement with a drive motor from the lathe. The split collar 76 isdisposed such that it is rotatable with respect to the opening 74. Thesplit collar 76 has a top surface 78 with a plurality of drive motorengagement notches 80 that communicate with the drive motor from thelathe in order to rotate the split collar 76.

With reference to FIGS. 7 through 12, the part clamping fixture 70 isshown in more detail. The fixture 70 includes a plurality of keys 82that fit into recesses 84 formed in the generally flat top surface 72.The keys 82 have fasteners 86 that pass through both the keys 82 and thegenerally flat top surface 72 to secure the keys 82 to a spacer plate88. The spacer plate 88 is disposed on top of a base plate 90 with thetwo plates 88, 90 being secured by standard fasteners 92 that extendthrough the generally flat top surface 72.

The split collar 76 has a bore 94 formed therein in which a toothed gear96 is disposed. The toothed gear 96 is secured to a puller member 98that, when lowered by the lathe, extends generally downward and intocommunication with the knuckle 12. The toothed gear 96 is rotatable withrespect to the split collar 76 and is supported at a bottom surface 100by a u-joint adapter 102 that has a central opening 104 formed thereinthat encompasses the puller member 98.

The part clamping fixture 70 has a right housing portion 106, a rightcover portion 108, and a right pull piston 110 disposed in the righthousing portion 106. The part clamping fixture 70 also includes a lefthousing portion 114, a left cover 116, and a left pull piston 118disposed within the left housing portion 114. Both the right pull piston110 and the left pull piston 118 are secured to the base plate 90 byrespective fasteners 112, 120. Each of the right housing portion 106 andthe left housing portion 114 are moveable with respect to the respectivepull pistons 110, 118 such that respective chambers 122, 124 are formedbetween each housing portion 106, 114. Each chamber 122, 124 has anorifice 126, 128 in fluid communication therewith allowing fluid toenter and exit the respective chamber 122, 124 to assist in moving theright and left housing portions 106, 114 upwardly and downwardly. Theleft and right chambers 122, 124 are sealed from their respectivehousings 106, 114 by a plurality of o-rings 130. Obviously any othersealing mechanism may alternatively be utilized. The left pull piston118 is preferably smaller in length and diameter than the right pullpiston 110 to ensure that equal forces are applied to the knuckle 12. Itshould be understood that the size of the pull pistons 110 and 118 mayvary depending upon the knuckle configuration.

As shown in FIG. 9, a bayonet 132 is preferably inserted into the spline40 defined by the inner surface 38 of the wheel pilot portion 36 of theflange portion 32. The bayonet 132 is for engagement with the pullermember 98 to lift the brake assembly 300, as described in more detailbelow. The bayonet 132 preferably engages a washer bore or face 133 inorder to lift the assembly 10.

As shown in FIG. 11, the right housing portion 106 is retained inproximity with the base plate 90 by a pair of retaining blocks 134. Eachof the retaining blocks 134 has a supporting portion 136 that engages aflange portion 138 of the right housing portion 106. Each of theretaining blocks 134 is secured to the base plate 90 by a fastener 140or the like. A pair of guide pins 142 are disposed in the right housingportion 106. Each of the guide pins 142 is secured to the base plate 90at an upper end 144 and each is in communication with a spring 146 at alower end 148. Each spring 146 fits within a recess 150 formed in thelower end 144 of each of the guide pins 142 and extends downwardly intocontact with the right housing portion. 106. The biasing force from thesprings 146 helps bias the right housing portion 106 away from the guidepins 142.

As also shown in FIG. 11, the right housing portion 106 includes a pairof bores 152 within which a respective piston 154 reciprocates. Eachpiston 154 moves between a normally unengaged position and a knuckleengaging position. The bores 152 are each sealed adjacent the outer ends156 of the pistons 154 by an end cap 158. The inner ends 160 of each ofthe pistons 154 has a gripper portion 162 and a swiveling gripperportion 164 which allow the piston 154 to engage and hold the upperstrut arm 155 of the knuckle 12 when the piston 154 is in the knuckleengaging position. Each piston 154 reciprocates within a bushing 166secured within the respective bore 152 to ensure proper alignment of thegripper portions 162 and the swiveling gripper portions 164 with respectto the upper strut arm 155.

Turning now to FIG. 12, which is a cross-sectional view of the fixtureassembly 70 through the left housing portion 114. The left housingportion 114 is also retained in proximity with the base plate 90 by apair of retaining blocks 168. Each of the retaining blocks 168 has asupporting portion 170 that engages a flange portion 171 of the lefthousing portion 114. Each of the retaining blocks 168 is secured to thebase plate 90 by a fastener 172 or other securing means. A pair of guidepins 174 are disposed in the left housing portion 114. Each of the guidepins 174 is secured to the base plate 90 at an upper end 176 and each isin communication with a spring 178 at a lower end 180 of the guide pins174. Each spring 178 fits within a recess 182 formed in the lower end180 and extends downwardly into contact with the left housing portion114. The biasing force from the springs 178 helps bias the left housingportion 114 away from the guide pins 174. The left guide pins 174 arepreferably smaller in length and diameter than the right guide pins 142.

As also shown in FIG. 12, the left housing portion 114 includes a pairof bores 184 within which a respective piston 186 reciprocates. Eachpiston 186 moves between a normally unengaged position and a knuckleengaging position. The bores 184 are each sealed adjacent the outer ends188 of the pistons 186 by a respective end cap 190. The inner ends 182of each of the pistons 186 have a gripper portion 194 and a swivelinggripper portion 196 which allow the pistons 186 to engage and clamp thelower ball joint 198 of the knuckle 12 when the pistons 186 are in aknuckle engaging position. Each piston 186 reciprocates within a busing188 secured within each bore 184 to ensure proper alignment of thegripper portion 194 and the swiveling gripper portion 196 with respectto the lower ball joint 198.

Referring now to FIGS. 9 and 10, which illustrate the puller member 98and the surrounding encasing 200. The puller member 98 has a headportion 202 around which the toothed gear 96 is located, a neck portion204 which passes through the opening 104 in the u-joint adapter 102, anda stem portion 206 which is rotatable within a bore 208 formed in thesurrounding encasing 200. The surrounding encasing 200 has a pluralityof bearings 210 disposed around the bore 208 to assist in the rotationof the stem portion 206.

The encasing 200 includes an upper body portion 212 that has an upperend cap portion 214 disposed thereabove, a lower end cap portion 216disposed therebelow, and a spacer portion 218 disposed between the upperbody portion 212 and the lower end cap portion 216. The components ofthe upper body portion 212 are held together by a fastener 220 or othersecuring mechanism. The encasing 200 also includes a lower stop portion222 which is secured to an upper end cap 224 by a fastener 226 or othersecuring mechanism. The upper body portion 212 and the lower stopportion 222 are surrounded by a body portion 228 having a stop portion230 secured thereto. The encasing 200 is preferably secured to theunderside of the base plate 90 by a plurality of fasteners 232, such asbolts or other securing mechanisms.

An upper reservoir 234 is preferably formed in the upper body portion212. The upper reservoir 234 is in fluid communication with a fluidinlet port 236 for receiving hydraulic fluid therein. The upperreservoir 234 is also in fluid communication with a first fluid orifice238 formed in the stem portion 206 of the puller member 98. The firstfluid orifice 238 is in fluid communication with an internal fluidpassageway 240 which is in fluid communication with a second fluidorifice 242 formed in the stem portion 206. Fluid that passes throughthe second fluid orifice 242 is passed into a lower reservoir 244. Thelower reservoir 244 is formed between the lower stop portion 222 and theupper end cap 224.

The stem portion 206 has an annular flange 246 integrally formedthereon. The annular flange 246 is preferably disposed in the lowerreservoir 244. The annular flange 246 and the upper end cap 224 are inmechanical communication through the inclusion of a plurality of springs248 disposed in recesses 250, 252 formed in their respective surfacesand a spring drive pin 254. Thus, as hydraulic fluid enters the lowerreservoir 244 through the second fluid orifice 242, the annular flange246 is caused to move upward against the force of the springs 248.

In operation, a brake assembly 300 which is to be refinished inaccordance with the process, as described in detail above, is located inthe lathe and generally beneath the part clamping fixture 70. The brakeassembly 300 is preferably resting on a pallet or other supportingstructure with unobstructed passages. After the brake assembly 300 hasbeen located on the pallet beneath the part clamping fixture 70, thebayonet 132 enters the spline 40 of the assembly 300 by passing upthrough the pallet upon which the assembly 300 is resting. The bayonet132 is pressed upward until a shoulder portion 256 contacts the washerface 133 of the flange portion 32 forcing it upward. The assembly 300 islifted by the bayonet 132 at least enough so that the wheel studs 44 areclear from the pallet 10.

Thereafter, the lathe lowers the puller member 98 and the pullerencasing 200 through the opening 74 and into communication with theknuckle 12. The stem portion 206 of the puller member 98 has a recess258 formed at its lower end 260 which is opposite the head portion 202.The recess 258 is non-uniform in diameter as in one orientation, it islarge enough to receive a rounded top portion 260 of the bayonet 132therewithin. However, when the stem portion 206 is rotated 90 degrees,its diameter is not large enough to receive the rounded top portion 260therewithin or to allow the rounded top portion 260 to be withdrawn fromthe recess 258 if it is positioned therein. Thus, when the puller member98 is lowered, it is oriented so as to receive the rounded top portion260 therewithin.

After the puller member 98 and the puller encasing 200 have beenlowered, the pair of right pistons 154 and the pair of left pistons 186are hydraulically actuated in order to apply a pinching or clampingforce to the knuckle 12. The right pistons 156 apply a clamping force tothe opposing sides of the upper strut arm 155 through the use of thegripper portions 162 and the swiveling gripper portions 164. Similarly,the left pistons 186 apply a clamping force to the opposing sides of thelower ball joint 198 through the use of the gripper portions 192 and theswiveling gripper portions 196. The lifting of the assembly 10 by thebayonet 132 and the lowering of the puller member 98 forces the knuckle12 into contact with the stop portion 230. The stop portion 230 has anannular shoulder 262 which engages knuckle 12. These actions locate thebrake assembly 300 within the lathe and also fix the knuckle 12 to thelathe separately from any drive mechanism. Further, the knuckle 12 actedon by the pullers and grippers so that the knuckle is fixed and located.The knuckle 12 is not exposed to any bearing pre-load force.

After the assembly 300 is located, the bayonet 132 is engaged byrotating the puller member 98 and the puller encasing 200 with respectto the surrounding body portion 228. The puller member 98 and the pullerencasing 200 are free to rotate with respect to the body portion 228 andare rotated 90° in order to engage the bayonet 132. Thereafter, aclamping force is introduced by applying pressure to the annular flange236 by introducing hydraulic fluid into the lower reservoir 244 throughthe second fluid orifice 242 forcing the puller 20 upward. By pullingthe puller member 98 up, the bayonet 132 is also pulled upward such thatthe lower stop portion 222 sits on the inner race 31 of the bearing 28in order to apply a force thereto and thus preload the bearing 28.

After the assembly 300 has been located and clamped as described above,the final finishing process of the inner and outer surfaces of the brakerotor 46 can be performed by a finishing tool. In such a process, thehub 14 is driven such that it and the brake rotor 46 are rotating withrespect to the knuckle 12 in which is fixed. The finishing tool is alsopreferably single tool such as a CNC tool, as is well known in the art.However, a variety of the other finishing tools may alternatively beutilized.

One of the features of the fixture assembly 70 is to turn the wheel hub14, the brake rotor 46 and the bearing 28 compliantly, such that thestem portion 206 and the annular flange 246 are free to float and followthe brake assembly bearing's axis of rotation. This helps control thedistance between the caliper ears and the rotor 46.

Referring now to FIGS. 13 and 14, which illustrate the brake assembly300 in accordance with a preferred embodiment of the present invention.The brake assembly 300 includes a knuckle 302 and a wheel hub 304. Theknuckle 302 and the wheel hub 304 have the same configuration as theknuckle 12 and the wheel hub 14 described in connection with FIGS. 1through 13. Thus, like parts will be identified with similar referencenumbers. In this embodiment, a brake rotor 306 is secured to the flangeface 34.

The brake rotor 306 has a cup 310 with a central aperture 312 formedtherein. The central aperture 312 is adapted to receive therethrough awheel shaft, which is affixed to the wheel and the rotor pilot portions36. The cup 310 extends generally actually from the flange face 34 andis dimensioned to receive the hub flange portion 32. The cup 310includes at is outer end an annular flange 312 having a plurality ofapertures 314 formed therein that lie in the same pitch circles diameterrelative to the wheel shaft as the wheel bolts 44 and having a similarpattern so as to accommodate the wheel bolts thereto.

As shown in FIG. 14, the brake rotor 306 has a pair of parallel annulardiscs 316 spaced from each other by a plurality of rectangular fillets318. The rectangular fillets 318 extend outwardly from the cup 310 anddefine an inner surface 320 and an outer surface 322 which act asbraking surfaces for a brake caliper 324.

The brake assembly 300 in a fully assembled condition has the wheelbolts 44 pressed through the wheel hub 304, the knuckle 302 rotatablyattached to wheel hub 304 by a bearing 28, and the brake rotor 306secured to the flange face 34 of the wheel hub 34. The wheel boltapertures 314 of the brake rotor 306 fit over the wheel bolts 44 with arespective lug nut 326 securing the brake rotor 306 fit over the wheelbolts 44 with a respective lug nut 326 securing the brake rotor 306between the wheel 328 and the wheel hub 304. The wheel 328 has a wheeltread 330 secured to the outer surface thereof, as is well known.Further, a drive shaft axle 332 is in communication with a half shaft334, which extends through the central aperture 312. A dust shield 336is preferably secured to the knuckle 302 and extends generally outwardlysuch that it lies parallel and adjacent to the inner surface 320 of thebrake rotor 306.

The brake caliper 324 is preferably disposed adjacent one portion of thebrake rotor 306. The brake caliper 324 has a pair of caliper pads 338,340 that contact the inner surface 320 and the outer surface 322respectively of the brake rotor 306. The actuation of the brake caliper324 and thus the caliper pads 338, 340 is well known in the art.

In accordance with the preferred method, the inner surface 320 and theouter surface 322 are subjected to a final finishing or refinishing. Thefinal finishing is preferably the same as discussed above, in connectionwith the wheel hub 304. This refinishing process, as discussed above,minimizes lateral run-out of the rotor with respect to the center ofrotation of the brake assembly 300. Further, the refinishing processallows for the control of distance between the caliper pads 338, 340 andthe inner surface 320 and outer surface 322, respectively. To accomplishthe refinishing process, the brake assembly 300 is preferably locatedinto a lathe machine and is processed, as discussed above. It ispreferred that the final finishing or re-finishing only be performed onthe surfaces 320, 322 of the brake rotor. Alternatively, however, thefinal finishing process can be performed on both the flange face 34 ofthe wheel hub 304 and the surfaces of the brake rotor 306.

As discussed above, the brake assembly 10 is preferably inserted intothe fixture assembly 70 in order to be properly finished such that thedistance and parallelism between the brake caliper pads 338, 340 and thesurfaces 320, 322 of the brake rotor is established.

Other objects and features of the present invention will become apparentwhen reviewed in light of detailed description of the preferredembodiment when taken in conjunction with the attached drawings andappended claims.

1. A method of finishing a brake rotor assembly, the method comprising:providing a knuckle, a brake rotor, and a hub; assembling said knuckle,said brake rotor, and said hub together to form an assembly; clampingsaid assembly in a fixture; finishing at least one surface of said brakerotor to reduce lateral run-out of said surface of said brake rotor toless than 14 μm wherein the assembly is clamped in the fixture duringthe finishing of the brake rotor wherein the finishing occurs prior tomounting of said brake rotor assembly to a vehicle.
 2. The method ofclaim 1, further comprising: providing said knuckle having a bearingretention structure formed therein.
 3. The method of claim 2, whereinsaid bearing retention structure is a generally circular bore formed insaid knuckle.
 4. The method of claim 3, further comprising: snap-fittinga bearing having an inner race and an outer race into said bore.
 5. Themethod of claim 4, wherein said bearing is located in said bore betweena lower shoulder portion and an upper snap ring.
 6. The method of claim1, wherein said hub comprises a flange portion.
 7. The method of claim6, further comprising: forming a relief channel in a face of said flangeportion and forming a plurality of bolt receiving holes in said reliefchannel.
 8. The method of claim 7, wherein said brake rotor is securedto said hub by a plurality of wheel bolts passed through a respectiveone of said plurality of bolt receiving holes.
 9. A method ofmanufacturing a brake assembly, said method comprising: providing aknuckle, a brake rotor, and a hub; assembling said knuckle, said brakerotor, and said hub together to form an assembly; fixing said assemblyto a fixture wherein said hub is driven such that said hub and saidbrake rotor rotate with respect to said knuckle; and finishing at leastone surface of said brake rotor to reduce lateral run-out of saidsurface of said brake rotor wherein the rotor is finished whileassembled to the knuckle and the hub and further wherein the finishingoccurs prior to mounting of said brake rotor assembly to a vehicle. 10.The method of claim 9, wherein parallelism between said at least onesurface of said brake rotor and a plurality of brake caliper ears ismaintained.
 11. The method of claim 9, wherein finishing said at leastone surface of said brake rotor to reduce lateral run-out of saidsurface comprises finishing said surface to have lateral run-out of lessthan 14 μm.
 12. The method of claim 11, further comprising: finishingsaid at least one hub outer surface prior to securing said brake rotorto said assembly.
 13. The method of claim 9, wherein reducing run-out ofsaid brake rotor minimizes lateral run-out to one or more brake pads.14. The method of claim 13, further comprising: press-fitting a wheelbolt into each of said plurality of bolt receiving holes prior to saidstep of finishing.
 15. A method of finishing a brake rotor, said methodcomprising: providing a knuckle, a hub, and a brake rotor, said brakerotor having an outer contact surface and an inner contact surface;assembling said knuckle, said hub, and said brake rotor to form a brakerotor assembly; securing said brake rotor assembly; rotating said brakerotor with respect to said knuckle; finishing said inner and outercontact surfaces of said brake rotor to have lateral run-out of lessthan 14 μm while the brake rotor is assembled to the knuckle and the hubwherein the finishing occurs prior to mounting of said brake rotorassembly to a vehicle.
 16. The method of claim 15, further comprising:controlling the distance between said inner contact surface and an innerbrake caliper between said outer contact surface and an outer brakecaliper.
 17. The method of claim 15, further comprising: controllingparallelism between said inner contact surface and an inner brakecaliper and between said outer contact surface and an outer brakecaliper.